Poly(tetramethylene ether) glycol (PTMEG), is a commodity in the chemical industry, widely used in the preparation of polyesters and polyurethanes. A variety of methods is known for manufacturing PTMEG, one being that disclosed in Belgian Pat. No. 853,028.
In that method, tetrahydrofuran is polymerized in the presence of acetic anhydride to form poly(tetramethylene ether) diacetate (PTMEA). This diacetate must then be converted to PTMEG. Conventional processes can be used for this conversion, but these leave soluble catalyst residues which contaminate the final product and may make it unfit for certain uses.
It has now been found, according to this invention, that the conversion can be easily accomplished to give nearly catalyst-free PTMEG if it is done by alcoholysis using an alkanol of 1-4 carbon atoms, and using as a catalyst an oxide, hydroxide or alkoxide of calcium, barium, strontium or magnesium .